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T E C H N I C A L I N S I G H T F O R W I R E L E S S P R O F E S S I O N A L Sw i r e l e s s . i o p . o r g
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WiMAX chases HSDPA VoIP crucial for convergence Mobile TV power woes
Debate grows over DTF testing
Concerto
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L E A D E R 5Convergence conundrum
U P F R O N T 6Motorola will buy TTPCom for £105 m
N E W S 7UK awards low-power licences
A N A LY S I S 9WiMAX: WiMAX is playing catch-up to 3GConvergence: Operators need to move on convergenceNetwork evolution: Network quality must bemaintained in evolution to HSDPA
O P I N I O N 13Cris da SilvaAll the right technologies are coming together tomake telecoms convergence more than just a “singlebill”, but operators must first get VoIP right.
F E E D L I N E S 14Debate grows over DTF testingThe growing trend to specify thresholds for distance-to-fault performance levels is worrying RFpractitioners worldwide.
M O B I L E T V 17Fuel cells could power mobile TV handsetsWireless service providers have seen the future –mobile TV to your handset. But such a power-hungryapplication drains batteries quickly. Portable fuel cellscould be the solution.
P R O D U C T F O C U S 21Advanced receiver maximizes HSDPA profitability● Roamers refresh tired mobile markets ● Concerto v6 benefits from Culham merger
P R O D U C T S 25Handset & Infrastructure
T H E F U T U R E 26HSDPA benefits from advanced receiverRoman Polz of Agere Systems explains why 1.8 Mbit/sis just not good enough for HSDPA.
3C O N T E N T S
JUNE/JULY 2006ISSUE 45
Institute of Physics Publishing Ltd,Dirac House, Temple Back, BristolBS1 6BE, UK.Tel: +44 (0)117 929 7481Editorial fax: +44 (0)117 925 1942Advertising fax: +44 (0)117 930 1178Web: wireless.iop.orgE-mail: [email protected]
EDITORIALEditor: Hamish Johnston;[email protected]: Paul JohnsonArt director: Andrew GiaquintoTechnical illustrator: Alison Tovey
ADVERTISINGSales manager: Simon Allardice;[email protected] co-ordinator: Jayne Boulton;[email protected]
MARKETING AND CIRCULATIONProduct manager: Angela Peck;[email protected]
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Monitoring network performance. p23.
Fuel cells may power mobile TV handsets. p17.
Roman Polz: new receiver for HSDPA. p26.
On the cover:Are DTF-test resultsbeing used properly?p14.
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N E W S I N B R I E F
WiMAX vendors must watch QualcommThe WiMAX industry must be mindful of Qualcomm patents covering OFDMand OFDMA technologies, warn analysts at ABI Research. Qualcommacquired significant OFDM-related intellectual property when it acquiredFlarion Technologies in 2005. According to ABI’s Philip Solis, “the companywill enforce [its OFDM patents] vigorously”. Soma Networks was the firstcompany to enter into a WiMAX-related royalty agreement with Qualcomm,signing an agreement in April 2006. Soma’s chief executive Yatish Pathaksaid: “It is crucial that Soma Networks guarantees our customers that wehave rights to key patents essential for OFDMA standards.”
Qualcomm and Nokia in UK patent disputeQualcomm has initiated legal proceedings in the UK against Nokia, allegingthat the Finnish handset maker has infringed upon Qualcomm patents. Theaction follows similar litigation against Nokia that was brought in the US.Qualcomm is seeking an injunction against Nokia in addition to damagescovering handsets already sold. The action covers patents related to phonesoperating on GPRS and EDGE technologies, but not CDMA technology.
MEMS handset market continues to growThe use of micro electromechanical systems (MEMS) in mobile handsets willcontinue to grow, with the market reaching $1 bn in 2010, says a report fromanalyst firm In-Stat. In 2005 the market was worth $157 m and is dominatedby microphones and bulk acoustic resonators. However, RF MEMScomponents may emerge in the future. According to In-Stat, this could occuras early as 2007 with the expected debut of MEMS RF switches, followed byMEMS oscillators in 2008. The report, MEMS – Making Their Mark in MobileHandsets, also notes that the ongoing drive to make handsets thinner andcheaper is boosting demand for MEMS microphones. In-Stat’s Frank Dickinsonbelieves displays, fuel cells and other types of MEMS could appear in mobilephones, but cautioned “suppliers of these devices may find a quicker path toprofit in other markets that have less demanding cost and size requirements”.
Fixed WiMAX will be stalled by mobile versionThe market for fixed WiMAX equipment adhering to the 802.16d standard will berestricted by the emergence of mobile WiMAX technology according to a reportfrom Juniper Research. Conforming to the 802.16e standard, certified mobileWiMAX products are expected in 2007. Juniper’s Aditya Kaul says that whencompared to its fixed counterpart, “mobile WiMAX offers a superior standard, afixed-wireless option and an immense value-add in mobility”. The report, FixedWiMAX: Opportunities, Strategies & Forecasts, 2006–2011, predicts that themarket for fixed WiMAX equipment will grow from $597 m in 2006 to $1.4 bn in2011. The report says voice services will account for a maximum of 11% of fixedWiMAX revenues, with the rest coming from data services. Small and medium-sized businesses will account for the bulk of fixed WiMAX users in the developedworld, while residential use will dominate developing markets.
Siemens gets 7140m in two Chinese dealsTwo Chinese GSM operators will buy 7140 m worth of network equipmentfrom Siemens. China Mobile will expand its GSM network using 790 m worthof Siemens equipment by the end of 2006, while China Unicom has agreedto buy equipment valued at 750 m. According to Christoph Caselitz,president of Siemens’ Mobile Networks Division, the deals will “ready thenetworks of China Mobile and China Unicom for the migration to 3G wirelessand [will] also strengthen our starting position for the award of 3G licences”.China is expected to issue 3G licences sometime in 2006 and Westernequipment suppliers are jostling to secure lucrative contracts.
Despite all the talk about data services and fixed-mobileconvergence (FMC), traditional circuit-switch voice-over-cellular continues to dominate mobile-phone usage sevenyears after the first 3G licence was awarded. And it is nowbecoming clear that voice – in the guise of voice-over-IP(VoIP) – will play a crucial role in encouraging consumers touse converged data services.
On page 13 Cris da Silva argues that the cost-effectivedelivery of VoIP services must be part of any convergencestrategy. He concedes, however, that delivering a full range ofvoice services over packet-data networks is going to be a realchallenge for operators. Voice services are subject to a broadrange of very strict regulations covering everything fromavailability to legal interception, and all eventualities must becovered by VoIP.
It is not surprising, therefore, that operators are reluctant tomove on convergence – especially while traditional mobilevoice services continue to fill their coffers. There is a generalconsensus, however, that increased competition in the mobileindustry is forcing a long-term downturn in voice revenues.On page 10, Richard Hubble implores mobile operators tomove on FMC as a way of maintaining or even boosting voicerevenues. Hubble argues that FMC will help operators retaincustomers as well as deliver a range of new data services –especially VoIP.
Both da Silva and Hubble agree that the 3GPP’s IPMultimedia Subsystem (IMS) will provide the core networktechnology to converge a wide range of wireless and wirelineservices. Unfortunately, IMS technologies are still in the earlystages of development and operators are finding it verytempting to put off any plans for convergence until thetechnology is more mature. Hubble believes that this is a bigmistake and operators that follow this course could lose out tothose that take an earlier and more aggressive stance on FMC.
UMA hinders convergenceOperators could move on FMC by using Unlicensed MobileAccess (UMA) technology. While UMA supports IP-basedvoice communications via Wi-Fi and Bluetooth, da Silvawarns that it is not compliant with converged core networks.As a result, the widespread deployment of UMA couldactually hinder FMC in the long term.
Instead, da Silva argues that true FMC will require bothIMS and the deployment of air interfaces that can serve largenumbers of VoIP users. This could be done on UMTSnetworks by deploying high-speed uplink and downlinkpacket-access technologies (HSPA) – or by deploying newmobile WiMAX networks. But HSPA rollout is in its veryearly stages and mobile WiMAX deployment has yet tohappen – so mobile operators will continue to delay onconvergence at their peril.
Hamish Johnston, Editor
Convergence conundrumE D I T O R I A LN E W S
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Motorola will buy UK-basedTTPCom Communications in adeal worth £105 m (6153 m).The directors of TTPCom haveagreed unanimously to accept theoffer, citing disappointing finan-cial performance as the main rea-son for the sale of the company.TTPCom revenues for the yearending 31 March 2006 were£37 m, down from £58 m theprevious fiscal year.
Motorola intends to buy allshares in TTPCom, which is cur-rently listed on the LondonStock Exchange. TTPComCommunications comprises twocore businesses and two joint-ventures. It owns TTPCom Ltd,which develops and licenses tech-nologies for use by chipmakersand mobile-phone manufactur-ers. It also owns ip.access Ltd,which produces cellular base sta-tions for indoor use. The com-pany is involved in a jointventure called 7 Layers UK Ltd,which provides testing and certi-fication services for handset mak-ers. TTPCom Communicationsalso owns a 12% share in Blaze,which creates mobile-entertain-ment products.
TTPCom chief executive TonyMilbourn said that Motorola isan “ideal partner for TTPCom”.He added: “This is an outstand-ing transaction for our com-pany.” According to thepresident of Motorola’s MobileDevices business group RonGarriques: “TTPCom is a leaderin wireless software platforms,protocol stack and semiconduc-tor solutions and is a highly com-plementary addition toMotorola’s mobile device tech-nology portfolio.”
TTPCom’s Tony Milbourn describedMotorola as an “ideal partner”.
Motorola will buy TTPCom for £105 m
Intel ups WiMAX investmentsIntel will provide funds to twotelecoms operators to assist in thedeployment of WiMAX net-works and services. Intel isinvesting in Orascom TelecomWiMAX Ltd, which is a jointventure between the chipmakerand Egypt’s Orascom Telecom.The venture intends to acquirelicences for the deployment ofWiMAX services in the MiddleEast and parts of Asia. OrascomTelecom currently operates sevenGSM networks in the MiddleEast, Africa and South Asia.
Intel is also providing funds toWorldmax, which is a joint ven-ture between Intel and EnertelHolding of the Netherlands.Worldmax intends to deliverWiMAX services in theNetherlands using a nationwide
3.5 GHz licence, which is beingsupplied by Enertel. Enertel sellswholesale telecoms services tooperators and businesses in theNetherlands and is also supply-ing funding and personnel toWorldmax.
Both ventures will be majorityowned by Orascom and Enertelrespectively, with Intel Capitalassuming the role of lead investorin both businesses.
Intel is a leading proponent ofWiMAX technology, whichpromises to deliver both fixedand mobile broadband wirelessservices in wide-area networks.The company has alreadyinvested in several aspiringWiMAX operators worldwide,including PIPEX Wireless in theUK and DBD in Germany.
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PCTEL closes Dublinantenna facilityPCTEL is closing its Irish manu-facturing facility, which producesvariable electrical tilt base-stationantennas. The US company plansabout 65 redundancies, but willcontinue its design and engineer-ing activities at the Dublin facil-ity. The production of its iVETantennas will be outsourced toElcoteq, which will use its facilityin St Petersburg, Russia.
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UK awards low-power licences
Nokia will pay InterDigital$253 million in outstanding roy-alties as part of a deal to end adispute over intellectual propertyrights between the two compa-nies. The royalties are related topatents on TDMA technologythat are held by InterDigital andare alleged to cover GSM/GPRS/EDGE handsets and infrastruc-ture equipment produced byNokia. The two companies haveagreed to withdraw from variouslegal and arbitration processesrelated to the patent dispute.
The two companies have alsoagreed to terminate their existingpatent licence agreement. Accor-ding to a statement from Inter-Digital, 3G equipment currentlyproduced by Nokia is unlicensedwith respect to InterDigitalpatents. “We remain hopeful thatwe can reach an amicable resolu-tion on this issue on termsacceptable to both parties,” saidWilliam Merritt, InterDigital’sPresident and Chief Executive.
The dispute began in 2003when Nokia refused to acceptterms similar to those defined in alicence agreement struck betweenInterDigital, Ericsson and Sony-
Ericsson. Commenting on thesettlement, Nokia’s Vice Presidentfor Intellectual Property RightsIlkka Rahnasto said: “This casedemonstrates that legal disputesare sometimes necessary in orderto lower unrealistic demands.”
InterDigital is embroiled in asimilar dispute with Samsung.An InterDigital spokespersontold Wireless Europe: “We believethat the resolution with Nokiacould help to facilitate discus-sions with Samsung.”
Twelve companies have beenawarded provisional licences tooperate low-power wireless ser-vices in the UK by sharing6.6 MHz of bandwidth at1800 MHz. While licence holdersare not required to deploy a spe-cific technology it is expected thatthey will use the spectra to deliverlow-power indoor GSM services.A key benefit of deploying GSMis that services can be delivered tomost existing mobile phones.
The spectra comprise 3.3 MHzbands starting at 1781.7 MHz and1876.7 MHz. These bands hadbeen reserved as guards betweenDECT and GSM services.
The licences were issued on theunderstanding that licensees willwork together to develop a code
of practice to minimize interfer-ence between services, rather thanhaving a code enforced by the UKregulator Ofcom. While this is aglobal first for the GSM industry,the relatively high frequency ofthe spectra, a 200 mW limit ontransmission power and mainlyindoor deployment should limitthe possibility of interferencebetween services. In areas whereinterference is likely – such aslarge public buildings or outdoorhotspots – operators could agreeto a frequency planning scheme.
According to Chis Cox ofip.access – which makes low-powered GSM picocellular basestations – most early deploymentswill be in business premises.Licensees could offer businesses a
private local mobile network thatdelivers PBX-like services such asshort-code dialling on conven-tional GSM phones. When hand-sets leave the premises, theywould be handed over to a stan-dard wide-area GSM network.
Provisional licences have beengranted to a wide range of estab-lished telecoms suppliers includ-ing O2, BT, Cable & Wirelessand Opal Telecom, which pro-vides telecom services to businesscustomers. Licences have alsobeen granted to foreign playerssuch as India’s Shyam Telecomand Spring Mobil of Sweden. Atthe other end of the industryspectrum, a licence has beengranted to the unknown UK-based Cyberpress.
Nokia opens Mass.research centreNokia and the MassachusettsInstitute of Technology (MIT)have opened a joint research facil-ity near Boston, US. The NokiaResearch Center Cambridge willdraw on expertise from MIT’sComputer Science and ArtificialIntelligence Laboratory todevelop technologies that can becommercialized in five to tenyears. The centre is focused onhow mobile devices could becomeelements within a pervasive infor-mation-based environment.
Handset productionto hit 1 bn in 2006In the first quarter of 2006,229 million mobile phones wereshipped, putting the industry ontarget to exceed an annual prod-uction of 1 billion units, claims areport from the analyst firmStrategy Analytics.
According to Neil Mawston,an associate director at the firm,the number of handsets shippedin Q1 2006 was 31% greaterthan the same quarter in 2005.Mawston said this is the “highestrate for almost two years”, andgrowth is “driven largely byemerging markets such as India”.
According to Q1 2006 GlobalHandset Market Share UpdateReport, Nokia continued toincrease its market share by com-manding 32.8% of the globalmarket in Q1 2006, up from30.9% in Q1 2005.
Second place Motorola alsoboosted its market share from16.5% in Q1 2005 to 20.1% in2006.
According to the report,Samsung was the only majorhandset maker to lose marketshare, dropping 1.4%.
Motorola buysBenQ R&D centreMobile-phone maker BenQ isselling its research and develop-ment centre in Aalborg,Denmark, to Motorola. The dealincludes the transfer of about250 employees to Motorola’sMobile Devices business unitalong with related developmentand test equipment.
The transaction is expected tobe completed in June 2006,when the Aalborg facility willbecome a product developmentcentre for Motorola.
Taiwan-based BenQ acquiredSiemens’ mobile-phone businessin 2005 and is in the process ofrestructuring its R&D and prod-uct-development operations inEurope.
Nokia and InterDigital resolve IP dispute
3G infrastructure from Nokia: InterDigitalclaims Nokia’s 3G infrastructure andhandset equipment are unlicensed withrespect to InterDigital’s intellectual property.
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Chris Tunsley argues that mobileWiMAX has a long way to go before itcan compete with 2G/3G cellular.
WiMAX has attracted much attentionthanks to its unique position in the wireless-technology market. Many fixed-wireless andwired telecoms companies see it as the way tostake their claim on a share of the mobilebroadband market. Some cellular operatorsview WiMAX as a threat to their plans todeliver true mobile broadband services. So itis not surprising that an intense informationwar has broken out with a broad range ofopinions being exchanged. Even industryanalysts who follow the progress of WiMAXhave published projections varying from“great success” to “niche market at best”.
Its proponents argue that WiMAX will bea better and cheaper alternative to cellularnetworks because it will deliver greater band-width. However, this view is flawed becauseit compares the 2G/3G systems of today withmobile WiMAX systems of the future.
The truth is that mobile WiMAX is in itsinfancy. The 802.16 standard was originallydeveloped as a fixed broadband wirelessaccess (FBWA) system. Like most IEEE stan-dards, WiMAX includes a basic standard plusmultiple variations. The FBWA system haslimited support for mobility so a project waslaunched to specify the 802.16e mobileWiMAX standard. Mobile WiMAX will beconsiderably more complex than other802.1x or WLAN standards and the specifi-cation won’t be complete until 2007 or 2008.Indeed, the first truly mobile systems willrequire mobility support beyond that pro-vided by the 802.16e standard and will prob-ably not emerge until the end of 2008. ThenWiMAX will likely have more in commonwith cellular networks than with FBWA.
This timescale could have a significantimpact on the ultimate success of the mobileWiMAX standard because by 2008 it willhave to contend with intense competitionfrom established 3G W-CDMA networks.While W-CDMA alone cannot deliver datarates comparable to WiMAX, the high-speeddownlink/uplink packet access (HSDPA andHSUPA respectively) upgrades will give 3Gdata rates a sufficient boost.
HSDPA is already delivering higher down-link data rates in a small but growing number
of 3G networks. The HSDPA standardsdefine 12 categories corresponding to differentmaximum data rates in the 1.8 to 14.4 Mbit/srange, which are all a significant improvementover the 384 kbit/s delivered by W-CDMA.
Of course, like most technologies, the theor-etical maximum is rarely achieved in practice.Indeed, in the foreseeable future it is likely thatnetworks will not support all HSDPA cat-egories. Operators are expected to target cat-egories 6 and 8, which deliver 3.6 and7.2 Mbit/s respectively and rates approaching3.6 Mbit/s have already been achieved on livenetworks with category-6 terminals.
Improvements in the uplink will beachieved by HSUPA, which brings greatersymmetry to uplink/downlink data rates.HSUPA now figures highly in operators’ roll-out plans and should be operational in 2008.
Relative costsBeyond speed, the relative cost of WiMAXis an important consideration. MobileWiMAX networks will require licensed spec-trum, which will increase the overall cost ofdeployment. While mobile WiMAX spec-trum will probably be cheaper than the orig-inal 3G licences, W-CDMA operatorsshould be able to acquire additional spectraat much lower rates. As a result, thelong-term price advantage forWiMAX will be minimal.
Several technical challengesmust also be overcome beforemobile WiMAX can beimplemented. Today thespecification is limited to thephysical and medium accesscontrol (MAC) layer stan-dards for the radio interface.These cover mobility-relatedfunctionality, such as pagingreception and handover sig-nalling. But they do notinclude specifications relatedto mobility managementwithin the network. Indeed,traditional 802.x specifica-tions are limited to the radio-interface functionality forlayers 1 and 2. This is suffi-cient for simple wirelesslocal-area or personal-areanetworks where networkmanagement functions
are not needed – or where simple manage-ment is distributed among ordinary nodes.
Mobile WiMAX network nodes must com-municate and exchange information withusers who are on the move. Multiple registersmust be interconnected; routers must relaythe user data; and intelligent network nodesmust perform several functions includingcontrolling the power of subscriber units.
In effect, all elements of the network infra-structure and related equipment for mobileWiMAX must be developed or acquired out-side of the traditional 802.x specifications.This could be achieved by implementing anentire mobile WiMAX system, which mayclosely resemble a cellular network. Such asystem would have to deliver the same qual-ity of service as a cellular network with lowlatency make-before-break handovers and nopacket loss. Indeed, the only practical way ofcreating a core network may be to use exist-ing 2.5G/3G network technologies. In thisscenario mobile WiMAX would coexist withand enhance part of existing mobile networksas defined by 3GPP or 3GPP2.
Mobile WiMAX’s ability to compete with2G/3G cellular networks is hindered by thefact that it will be deployed several years after3G and because the standard does not define
the entire network infrastructure.Instead, WiMAX will notcompete directly with2G/3G services but will formpart of future cellular net-works. For exampleEUTRAN – the 3GPP’svision of an evolved 3G radioaccess network – will sharemany features with the802.16e physical layer. As aresult many WiMAX tech-nologies – if not the standarditself – could be an impor-tant part of 3.5G/4G cellularnetworks of the future. It isalso possible that WiMAXaccess points will be con-nected to the 2G/3G corenetwork, allowing WiMAXto be an additional accessnetwork technology. ■
Chris Tunsley is ProductManager for protocolsoftware at TTPCom
W I M A X
WiMAX is playing catch-up to 3G
Mobile WiMAX is still in development whilefully-mobile 3G data services are available
today on handsets such as Motorola’s A1000.
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Converged mobile services will change thetelecoms world forever. Operators that ignorethis reality face an uncertain future, whilethose that embrace convergence could ben-efit from a wide range of opportunities thatlie ahead. Fixed mobile convergence (FMC)will enable operators to offer truly differen-tiated services to subscribers regardless oftheir location, their access technology, or thedevice they choose to use.
The ability to offer mobile services isallowing fixed-line operators to fill the grow-ing financial void created by the ongoingdrop in their voice revenues. FMC could alsohelp mobile operators, which are also strug-gling to maintain voice revenues while com-peting in an ever-crowded arena ofestablished players and upstart mobile virtualnetwork operators (MVNOs). While somecellular operators seem prepared to gambleheavily on the success of 3G to replace thesefalling voice revenues, 3G network coverage(which remains sporadic) and performancehave yet to emerge as powerful service dif-ferentiators.
While voice revenues face decline, there isgrowing interest in Internet protocol (IP) ser-vices such as voice-over-IP (VoIP) and richmultimedia services. These services areenabled by converged infrastructure and net-work agreements that will lift forward-think-ing service providers above the competitionand allow them to differentiate their servicesbeyond price.
FMC will allow a wide range of serviceproviders to extend their traditional offer-ings, while allowing them to deliver moreadvanced services over IP networks. This is
much more attractive than the more costlyalternative of installing multiple purpose-built networks for different applications ortraffic types. Convergence allows a providerto deliver services on their own network aswell as to subscribers roaming on other net-works or even on private networks.
Strategy goalsAn effective FMC strategy should achievetwo important goals – increase subscriberretention and allow operators to develop newand richer service opportunities such as VoIPor intelligent content delivery. By achievingthese goals, operators can deliver truly dif-ferentiated services, more robust voice ser-vices and enjoy genuine revenue growth.
In the US, for example, mobile operatorsare promoting “in-network plans”, whichoffer free mobile-to-mobile calls for sub-scribers on the same network. Graduallythese plans are being extended to includelandlines, or even home VoIP phones. Togenerate revenue from such services, opera-tors could provide subscribers with a singleidentity or number broadly applied not onlyto voice services, but across a variety of net-works and devices covering applicationsincluding multiple messaging formats and
Operators mustmove now onconvergenceFixed-mobile convergence will keep mobile operators growing despite fallingvoice revenues, says Richard Hubble.
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content. Subscribers could also be given theability to optimize the delivery of these ser-vices by selecting the highest performancenetwork or the lowest cost alternative,depending on the specific application orusage scenario.
In European markets such as the UK,operators are facing other business pressures.While these markets are competitive, the rel-atively high cost of mobile services presentsan ideal environment for insurgent operators.UK mobile subscribers are very experiencedin buying and using mobile services andtherefore, by offering the right products, aninsurgent could command a very large andlucrative market.
CompetitionWhile large incumbent operators are in thebest position to capitalize on these newopportunities, they will quickly becomeexposed to competition from new players ifthey fail to deliver desirable services. This isespecially true for more traditional operators,which stand a very real chance of being rele-gated to lower cost bit pipe providers withsimple voice minute or data usage bundles.
The intense pressure on voice revenues isevident in financial statements from leading
global operators. Vodafone, for example,recently declared voice-revenue growth of3.9% – compared with 5.6% for messagingand 28.1% for data services. These figuresmake it very clear where the new revenues willcome from in the future. As time progresses,revenues from basic data services will level offonly to be surpassed by growth in revenuesassociated with content and applications.
Service providers must follow a practical andgraceful migration path towards convergedservices. This migration must allow them toreap all of the benefits of introducing richerand differentiated services to their customerstoday, while making full use of existing net-works to deliver a rapid return of investment.
While the next-generation network, IPmultimedia subsystem (IMS) standard pro-vides the right long-term direction for evolu-tion, operators cannot wait for IMS. Insteadthey must begin with technologies that deliverresults today, while gracefully migrating to amore flexible IMS infrastructure over time.
Service providers that ignore the realities ofdeclining voice revenues will suffer financialstrife in the long term, whereas those whoembrace new opportunities could reapimpressive returns on their investment.Indeed, not participating in this brave newconverged world of telecommunications isno longer an option for any operator.Unfortunately many operators make theirfirst steps towards IMS in a defensive reac-tion to a competitor – but it does not haveto be this way. ■
Richard Hubble is EMEA Director for TataraSystems.
More than just voice: operators must also deliver a wide range of data services over converged networks.
Service providers thatignore the realities ofdeclining voice revenueswill suffer financial strife
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Igor Leprince navigates the network-upgrade maze from 2G to HSDPA.
Third-generation networks and services arestarting to make their commercial mark inWestern Europe. In the UK alone, about4 million 3G handsets were estimated to bein use by the end of 2005. Meanwhile in theUS, Cingular has pushed the boundaries of3G by launching commercial HSDPA ser-vices in late 2005.
The industry is now eagerly anticipating astring of HSDPA commercial launchesthroughout Europe. Despite real progress,there is still much work to be done beforeHSDPA can be declared a commercial reality.Indeed, network operators still face signifi-cant challenges as they upgrade their networkinfrastructures from 2G to 3G.
While some commentators liken the cur-rent migration process to the mid-1990s evo-lution from first generation analogue servicesto 2G digital technology, such comparisonsare misguided. In reality, the European cellu-lar landscape has changed radically over thelast decade. In many markets, more than 90%of the population are mobile subscribers andcustomers’ expectations regarding the qualityof service (QoS) have risen dramatically. Onthe network side, a decade of expansionmeans that many prime base-station sites arealready taken, and environmental regulationsgoverning base stations in Europe are nowamong the most stringent in the world.
While the challenges are many, QoS is aclear priority for 3G operators. When build-ing next-generation networks operators mustensure that the new network can deliver aQoS that at least matches that of existingtechnologies – today’s sophisticated cus-tomers will accept nothing less.
Quality does not come cheap, so cost isanother important issue related to the migra-tion process. Overhauling all 2G sites requiresmassive investment to make extensiveimprovements to their technology infrastruc-ture. Operators may even need to renegotiateleases on buildings in the networks.Throughout this upgrade process operatorsmust also deal with significant constraints on
their capital and operating expenses. It is natural therefore, that operators with
2G networks seek to make use of existinginfrastructure by collocating new 3G equip-ment within an existing 2G site. Whileattractive on the surface, there are often sig-nificant complications with this approach.Sometimes upgrading an existing 2G facilityis simply not possible due to space limita-tions or issues related to site acquisition. Thedifferences between 2G and 3G networksextend well beyond technology and includesubscriber behaviour. 2G phones are usedprimarily for voice calls, while a typical 3Gcustomer would also be downloading video,sending emails or listening to music.
Demanding usersAnd even when possible, upgrading a 2Gnetwork may not provide the operator withthe necessary QoS levels to satisfy its sub-scribers. Indeed most operators still have agreat deal of work to do in upgrading andoptimizing their existing networks to deliverthe appropriate QoS. This is best achieved bydrawing on the services of an independent
company with the experience of working ona broad range of networks from differentvendors, based on multiple technologies andlocated in numerous regions.
Once 3G has been implemented, the nextstep is the addition of high-speed downlinkpacket access (HSDPA) functionality.HSDPA has the potential to boost downlinkdata rates by up to five times that of current3G networks. HSDPA is very attractive to3G operators because it allows them to boostthroughput across the network by makingan incremental investment in new technol-ogy that is estimated to be no more than 5%of the cost of their original 3G network.However, to benefit fully from HSDPA,operators must also ensure that their back-bone and transmission networks can copewith increased data traffic.
HSDPA is a new technology and thereforeone of the key challenges facing operators isdetermining what service levels can beachieved. HSDPA network performance canvary significantly as a function of networkdesign and optimization or even the layout ofthe building being covered. In practice,
The BenQ-Siemens EF91 promises to be the first commercial HSDPA handset for Europe when it debuts in mid-2006.Operators must ensure their HSDPA networks deliver appropriate QoS levels to users of the EF91 and other HSDPA terminals.
N E T W O R K E V O L U T I O N
Network quality must bemaintained in evolution to HSDPA
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extensive initial trialling is the only way todetermine what service levels can be attained.
Operators can make a direct comparisonwith 3G performance by performing trialsthat determine the HSDPA customer expe-rience. While HSDPA can theoretically boost3G downlink data rates by up to five times,this might not be possible in all local envi-ronments. Variables such as the location ofthe user (including their distance from thebase-station antenna), whether the user ismoving or stationary, and the presence ofshadowing effects can all have a major impacton downlink performance.
Operating costsAs ever, money is another key concern foroperators planning HSDPA upgrades.Additional operating expenditure (opex) willbe low if the network is not heavily loadedwith traffic. However, as more subscribersswitch to 3G, and high-speed services areadded, operators may need to upgrade theirnetwork infrastructure further and ultimatelyinstall new backhaul links – which wouldlead to a dramatic increase in opex.
HSDPA-related increases to opex could besignificant. Each new E1 backhaul transmis-sion link would cost about £1500 (62200) toinstall and about £2500 per year to lease. Fora large network with 10 000 base-stationsites, this could end up costing £30–40 mil-lion. Operators must prepare for high expen-diture to ensure their networks can supportthe traffic that will be generated by new tech-nologies and associated services.
There are several important steps that anoperator can take to ensure that their networkis upgraded to accommodate new technolo-gies. Perhaps the most important is the need totake advantage of expert consultancy through-out the upgrade process. To add real value,operators must choose a consultancy that has acomprehensive understanding of the relevanttechnologies. The consultancy must act as agenuine business partner, explaining what therelevant technologies can deliver and makingthem relevant to their customers’ needs.Crucially, all advice must be independent andvendor and technology neutral.
In the long run, taking advantage of expertadvice should enable carriers to save signifi-cant sums of money and, critically, will alsoallow them to ensure the delivery of highQoS on their networks. Ultimately, successwill be measured in terms of happier cus-tomers, lower rates of churn, increased useof services and revenue per user and the com-petitive edge over other operators. ■
Igor Leprince is EMEA managing director atWFI.
All the right technologies are coming together to maketelecoms convergence more than just a “single bill”,but Cris da Silva argues that operators must first getVoIP right.
C R I S D A S I L V A
Fixed-mobile convergence (FMC) and convergence within fixed networks are drivinga wide-ranging transformation of the telecoms industry. Both are underpinned bythe triumph of Internet protocol (IP) and related technologies, which are the mosteffective way to create and deliver new value-added services. However, voice is stillthe “killer application” and therefore the cost-effective delivery of voice-over-IP(VoIP) services will be crucial to the success of any convergence strategy.
Convergence within fixed networks is being driven by the triple-play serviceoffering of high-speed Internet, fixed-line telephony and IPTV/video-on-demand.Today these services are usually delivered via three different networks – indeed, voiceservices are often provided by reselling public switched telephone network (PSTN)services from incumbent operators. Although today’s triple-play services are based onprimitive technologies and minimal network integration, their growing popularitysuggests significant revenues that can be unlocked by offering truly convergedservices over next generation networks (NGNs).
NGNs will merge the traditional PSTN and the new IP-based video and datanetworks. They will allow operators to reuse network elements to provide basicfunctions such as session control, billing, QoS policy, authorization and authenticationacross all IP-based services. However, supporting a full range of voice services over apacket network is going to be difficult. Voice is not just any other service because it issubject to strict regulations on availability, emergency calls and legal interception. Inaddition, legacy “dumb” terminals must continue to be supported.
As a result NGNs must provide costly PSTN emulation services (PES), which willerode the already slim profit margins associated with traditional voice services. To
offset this cost, and generate new higher-marginrevenue streams, fixed-line operators mustintroduce new and advanced multimediacommunication services.
This is where the 3GPP’s IP MultimediaSubsystem (IMS) comes to the fore. Althoughdeveloped for mobile networks, IMS provides acore network that supports the introduction of a
completely new set of IP-based services as well as supporting a PES. However, itsgreatest asset is that IMS is largely access-network independent, which leads nicely tothe other convergence trend – FMC.
Unlicensed Mobile Access (UMA) technology is currently at the vanguard ofFMC. UMA allows a multi-radio handset to switch between a GSM network and aBluetooth or Wi-Fi access point. When the handset switches to a local access pointall GSM traffic is carried as IP packets and GSM protocols are used in conjunctionwith GSM circuit-switched core networks. However, UMA is not compatible withconverged core networks and therefore UMA will ultimately hinder FMC. Indeed,only IMS can deliver a wide-ranging transformation that is access-networkindependent. True, FMC also requires an air interface that can serve large numbersof VoIP users in a macro cellular environment – something that both HSPA andmobile WiMAX are in a good position to deliver. ■
Cris da Silva is Consultant in Wireless Technology at PA Consulting Group. He can becontacted at [email protected]
UMA is not compatiblewith converged corenetworks and willultimately hinder FMC
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Bruce Holsted has been troubleshooting and repairing anten-nas and feed lines for 15 years and is of the firm opinion that thenew trend towards setting thresholds for distance-to-fault per-formances is a move in the wrong direction. An increasingnumber of operators and consultants across Europe and NorthAmerica are specifying a minimum level of performance in theDTF test. Holsted says that this trend demonstrates a misunder-standing of the nature of the test, which he believes is inherentlyqualitative rather than quantitative. Holsted says his company,which is based in Arkansas, US, has a firm policy: “We ask at thefront end about the customer’s testing specification, and if theydemand a particular DTF figure with the antenna connected,then we generally don’t do the work.”
While maturity and experience allow Holsted and his team tomake such decisions, he believes less experienced RF test andmaintenance technicians are responding to thresholds in a worry-ing way. He says some site-construction representatives are encour-aging technicians to loosen cable connectors until the specifiedDTF figure is achieved. He describes this practice as “absolutelyinsane” and contrary to the purpose of the DTF test, which is tofind possible problems with the cable/connector installation.
Interpreting resultsAt the root of this controversy is the fact that modern test equip-ment allows an inexperienced user to make complex measure-ments without knowing how to interpret the results fully. Thetwo relevant measurements are the DTF test and the related volt-age standing wave ratio (VSWR) test. The VSWR, or return losssweep test, measures the ability of the entire transmission line –including jumpers, connectors and any other in-line elements –to deliver maximum power to and from the antenna with mini-mum signal distortion. A ratio of transmitted versus reflectedvoltage, the VSWR is a vital quantitative measure of the line’simpedance match with the transmitter or receiver at one end, andthe antenna at the other. In essence, it measures the line’s ability tofulfil its job of transmitting RF power or receiving an RF signal.
The VSWR test result is frequency-dependent, and so thetest is undertaken across a range of frequencies corresponding tothe operational requirements of the installation. Test results areshown in figure 1 as a plot of either return loss (measured indecibels) or VSWR, versus the sweep frequency.
DTF testing, on the other hand, is an inherently diagnostictest that is performed in the time- rather than frequency-domain. “It works on the same principle as radar,” explainsVincent Benevento, who is applications engineering managerat Radio Frequency Systems (RFS). “The earliest time domainreflectometer (TDR) testers output a step or pulse into thecable. When the pulse encountered a discontinuity, some ofthe signal was reflected back. The amount of time it takes for the
signal to return can be converted to distance along the line, andprovides an approximate location of the reflection point.”
Discontinuities that can cause significant reflections includedamaged cable, improperly installed or mated connectors andwater ingress. The shape and nature of the DTF pulse responseplotted against line distance can provide valuable diagnostic data(figure 2). “When a high VSWR is encountered, a DTF test canprovide information to help locate the source of the high VSWR,”Benevento says. “This avoids randomly changing out componentsto find the fault.” The DTF test can also provide a “birth record”for the transmission line. This allows maintenance crews to com-pare current performance with that achieved at installation.
Advances in the data processing power of site-testing equip-ment have permitted VSWR and DTF to be combined into asingle frequency-domain based test instrument. “The modernnetwork analyser uses frequency-domain reflectometry to actu-ally simulate the time-domain DTF test,” says Benevento. Thisis done using the inverse fast Fourier transform technique,which uses data obtained during a return loss or VSWR sweeptest to calculate the DTF response.
The procedure for the VSWR or return loss sweep test is fairlystraightforward and well-understood. “What you see in theVSWR test is a functional check of the entire transmission systemas it shall be operated in later life,” says Gerhard Wunder, DirectorInternational Business Development Transmission Lines at RFS.Wunder recommends the installation should first undergo a visualinspection followed by a test that sweeps across the entire opera-tional frequency band to ensure that the reflected power is withinspecifications. “It’s a highly repeatable test,” he says.
Return loss can be measured with a 50-ohm standard load putin place of the antenna. “Typically, with the 50-ohm load inplace of the antenna, we’d expect to see a return loss of betterthan 23 dB. This depends, of course, on the length of the line. Ifwe don’t achieve these minimums, then we VSWR-test the linein sections to isolate the problem.”
Check listBruce Holsted says that the first step is to check that cable con-nectors are tight and free of moisture. Then the antenna and anytower-top amplifiers are then disconnected while VSWR is usedto prove the feed line. Finally, a RF series adaptor is placedbetween the jumpers and the antenna is proven.
While the all-in-one site network analyser is convenient, it isimportant to recognize the limitations of the DTF test resultsobtained – particularly the erroneous application of a pass/failthreshold. “There are a number of parameters that impact onthe quantitative results that come out of a modern DTF test,”says Wunder. “From this point of view, it is illogical and sim-plistic to apply a site-wide DTF performance threshold.”
Debate grows over DTF testingThe growing trend to specify thresholds for distance-to-fault performance levels is worrying RFpractitioners worldwide. Joerg Springer explains.
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Indeed, even the cable length will affect the DTF reading. Thelonger the cable, the narrower the bandwidth sweep that can beperformed. This reduces the resolution of the instrument andreduces its ability to resolve closely spaced reflections. As a result,transmission lines of identical diameter and installation quality,but of differing lengths, can produce different DTF results.
However, of greater concern is that the DTF is not being mea-sured directly, but is calculated. As a result it represents an esti-mate of the average return loss over the frequency range beingswept. “This really explains the ‘non-repeatable’ nature of DTF,”Wunder says, adding: “It is this inherent calculated and averagednature of the DTF test that can result in dramatic differencesin the measurements taken just by varying test conditions suchas test bandwidth or cable length.”
Random thresholdsVincent Benevento points out that one of the most tediousaspects of dealing with thresholds is the somewhat nominalmanner in which they are selected. A number of operators, hesays, are applying a DTF measure that can be difficult to achievewith the specified transmission line components.
“The cable connectors might be specified at 30 dB. Now ourconnectors generally perform better than [this] so an averageconnector DTF performance level might be, say, 36 dB,”Benevento says. “The problem is that some carriers are takingthis performance level of 36 dB and applying it as a blanketthreshold!” He also points out that gaining another 1 or 2 dBof DTF performance at such a low level has little or no impacton the overall system performance.
Benevento cites a recent installation in the US state of NewJersey, where his team was asked to inspect several connectionsthat were apparently failing DTF tests. “The site DTF threshold
specification was ‘34 dB or better’, so the installation crew wascutting these connectors and changing them out,” he says.“When they opened the ‘failed’ connectors they found they wereperfect – nothing was done wrong and they looked great.”
A DTF sweep of all transmission lines on the site revealedthe true purpose and value of the test. “The connectors were allrunning at the same sort of level, between 32 and 34 dB. Thenwe hit one running at 26 dB. Sure enough, when we opened itup, the flare inside the connector was all bent over and crushed.Now that is what the DTF test is supposed to be used for.”
Such incidents make it clear why Bruce Holsted describesDTF performance thresholds as “the bane of the industry rightnow. Why they establish this DTF threshold is beyond me – Idon’t know whose idea that was. It’s just ignorance.”
While Benevento is adamant that the DTF test has a vitaldiagnostic role to play, he believes that it is misused when athreshold is arbitrarily defined as a pass/fail criterion. “Thethreshold should not be a pass/fail requirement, but one thattriggers an investigation into whether connectors are properlyinstalled or if there is cable damage,” he says. Gerhard Wunderemphasizes the cost and waste associated with the misuse andmisinterpretation of the DTF test results, which has site testingcrews out “chasing ghosts [and] trying to achieve DTF valuesthat are impossible or unachievable”.
Bruce Holsted cites the “push-button” nature of the modernnetwork analyser as the root cause of some DTF-related prob-lems. He believes that it is now simply too easy to achieve whatappears to be an accurate plot of DTF versus line length.Indeed, Holsted recommends that engineers go back to basicsand gain a true understanding of the test being carried out. ■
Joerg Springer is at Radio Frequency Systems.
100
–10
–30–40–50
start 1 850.000 MHz stop 1 990.000 MHz
1
(dB)
1: reflection log mag
1
10.0 dB/ ref –20.00 dB Cmeas 1: Mkr1 1898.650 MHz
–27.753 dB
–20
–30
start 0.00 ft stop 100.00 ft
5.0 dB/ ref –20.00 dB2: fault log magmeas 2: Mkr2 6.13 ft
–39.981 dB
2
–35 2
1 34
C
(dB)
–40–45–50–55–60
Modern test equipment can perform distance-to-fault (DTF) testing of RFtransmission lines with the push of a button. While DTF tests provide powerfuldiagnostic data, there is growing concern that this information is not beinginterpreted properly.
Fig. 1. Return-loss measurements such as this typical plot are performed overa specific frequency range.
Fig. 2. The shape and nature of the DTF pulse response plotted against linedistance provides valuable information regarding the transmission line.
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Mobile TV is shaping up to bethe next big thing for mobilephones. Commercial services arealready available in South Koreaand Japan, with network opera-tors poised to launch in Europeand North America. Yet whilemobile TV is here today, there aretechnological, standardizationand regulatory hurdles that mustfirst be overcome in order forcommercial services to flourish.Many of the problems relate tothe fact that mobile TV is a verypower-hungry application, some-thing that worries HitomiMurakami, vice-president, cor-porate technology sector atKDDI Japan. As the secondlargest cellular operator in one ofthe most advanced markets formobile telecoms services, KDDIalready offers mobile TV services via the One SegmentBroadcasting (One Seg) standard.
On the upside, it’s clear that mobile TV services could ulti-mately make money – and lots of it – for telecoms operators inJapan and elsewhere. The downside is that these new video ser-vices also pose a threat to the telcos’ bottom line. For starters,TV viewing quickly drains the handset’s battery, leaving usersunable to access other broadband services. Murakami believesthat traditional lithium-ion batteries are reaching the limits oftheir capability – so much so, in fact, that they are unsuitable formobile TV and other digital broadcast services. He estimatesthat a typical mobile phone will only be able to offer about twohours of TV viewing per battery charge.
While mobile subscribers are not likely to watch several hoursof TV at a time, Murakami believes that it will still further erodethe useful lifetime of a mobile handset. He cites a 2004 surveyin Japan, carried out before mobile TV services were available.At this juncture, about 80% of respondents had already experi-enced difficulties caused by battery shut-down. The survey
revealed that most users rechargetheir handset batteries daily, butwould rather do so every secondday. The feedback also suggestedthat limited battery life was pre-venting subscribers from usingtheir handsets as frequently asthey would like.
Murakami is adamant that fuelcells are the only way to meet theincreased power requirements thatcome with mobile TV. “I believethat all handsets will move to fuel-cell batteries,” he says. In additionto higher energy densities,Murakami says that fuel cells area more environmentally friendlyoption than batteries, another fac-tor that will encourage the shifttowards fuel-cell adoption.
In terms of cost, Murakamiconcedes that fuel cells will be “a
little bit higher priced” than lithium-ion batteries in theJapanese market. “However, within a few years, there will beno [cost] difference to that of existing lithium-ion batteries.”Murakami also remains adamant that handset makers will nothave to introduce any significant changes to their handset designor manufacture, largely because portable fuel-cell systems havebeen designed to be compatible with existing batteries.
The power of video Right now, KDDI is working with two handset makers, Toshibaand Hitachi, to develop direct-methanol fuel-cell (DMFC) powersources. The Hitachi prototype is based on the W32H handsetand the DMFC is said to deliver 300mW power output and aboutthe same energy capacity as a conventional battery from a 3 mlcharge of aqueous methanol. The addition of the fuel cell doesnot change the size of the handset, but adds about 24 g in weight.
Meanwhile, Toshiba has created a pilot model with a built-inDMFC. The fuel cell operates on concentrated methanol and hasa fuel capacity of 7 ml. It has a 300 mW power output, with
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Fuel cells could powermobile TV handsets
Wireless service providers have seen the future – mobile TV to your handset. But such a power-hungryapplication drains batteries quickly. Hamish Johnston finds portable fuel cells could be the solution.
“All handsets will move to fuel-cell batteries,” says KDDI’s Murakami.
1 8 M O B I L E T V
double the energy capacity of conventional batteries. The hand-set is based on Toshiba’s A5509T model and weighs 160 g. This is47 g more than a standard battery-powered A5509T; the DMFCalso adds 14 mm in thickness to the phone (when folded).
CommercializationAccording to Murakami, Toshiba intends to commercialize thistechnology in 2008 by producing a DMFC that can deliver 1 Wwith a storage capacity around five times greater than that ofconventional batteries. Murakami says that there are no tech-nological barriers in the way of launching such a device. Instead,he says that KDDI is “investigating market needs such as price,standardization and how to sell [fuel-cell-powered handsets] inthe Japanese market”.
Regulatory issues surrounding the transport of methanolonboard passenger aircraft are also in a state of flux. Currently,
passengers are not allowed to carry methanol onboard aircraft.However, Murakami is confident that this will change byJanuary 2007, when the International Civil AviationOrganization (ICAO) is expected to authorize airlines to allowpassengers to carry fuel-cell devices onboard planes. “I under-stand that the standardization effort is now under way at theUN jointly with ICAO and IATA [International Air TransportAssociation],” he said, adding that he expects all airlines andcountries to allow methanol-powered devices onboard planes.
Other regulatory and standardization issues include those sur-rounding the sale and storage of methanol and the standardiza-tion of the fuel and fuel cartridges. Murakami also notes that thereare intellectual-property issues related to DMFCs that will need tobe addressed before there is widespread commercialization. ■
Hamish Johnston is editor of Wireless Europe.
J u n e / J u l y 2 0 0 6 wire less. iop.org w i r e l e s s e u r o p e
I n n o v a t i v e S e m i c o n d u c t o r S o l u t i o n s
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Man-Machine Interface Illumination Sensor, Power Booster, TFT Display, TFT Driver, LEDs and Drivers
Base Band and MultimediaDynastron Camera, SoC for Mobile Phones, Multi-Media Engine, System Memory, Removable Memory
Common Components
RF Discrete Components
Moving pictures, on the moveKDDI’s Hitomi Murakami is not alone in thinking that mobile TV will bea runaway success. Technology trials in Europe suggest thatconsumers are willing to pay up to $15 per month for TV services totheir handset. That’s music to the ears of the wireless telecomsindustry, which is currently struggling to get subscribers to pay forservices beyond basic voice and text messaging.
Like many cellphone technologies, mobile TV is being pioneered inJapan and South Korea, though interest is growing in other markets.Korea-based Samsung recently released a mobile TV handset for theEuropean market that uses the Terrestrial Digital MultimediaBroadcasting (T-DMB) standard. Commercial T-DMB services began inSouth Korea last year and German subscribers could watch World Cuphighlights via T-DMB in June.
Samsung is also developing chips for the rival Digital VideoBroadcast-Handheld (DVB-H) mobile TV standard. Championed by theleading handset maker Nokia, DVB-H is the subject of a number oftrials in several European countries. Across the Atlantic, meanwhile,the cellular-base-station operator Modeo intends to launch DVB-Hmobile TV services in several US cities.
Mobile TV can also be delivered using the digital audio broadcast
standard and a major trial of this has been completed by BT in theUK. Other mobile TV standards include MediaFLO from Qualcomm andTDtv from IPWireless.
Fuel cells are the only way to meet the power requirements of mobile TV.
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Throughout the world, established mobileoperators with high subscriber penetrationrates face the same key challenges. Theseinclude how to address the continuous dropor possible reduction of the average revenueper user (ARPU) from voice services and howto boost ARPU by introducing a range ofother services and applications. While oper-ators don’t know what the next killer applica-tion will be, most are convinced that themost sensible way forward is to provide sev-eral interesting services and applications onthe mobile devices and let consumers choosefor themselves.
Operators must also plan for the emergenceof possible disruptive technologies such asvoice-over-Internet protocol (VoIP), whichcould be both a threat and an opportunityfor mobile operators. VoIP-based services thatare enabled and supported from within an IPMultimedia Subsystem (IMS) environmentcould allow operators to offer new applica-tions and services that both business users andconsumers are willing to pay for.
Many of the current and emerging serviceswill put increased demands on networkthroughput and total available capacity.These high-bandwidth services includedownloading games, person-to-person gam-ing, music download, video streaming, videosharing, video calls, video conferencing, webbrowsing, and multimedia broadcast multi-cast services (MBMS). To ensure the successof these and other services, operators areupgrading their networks with high speed
downlink packet access (HSDPA) capabilitywhich can provide peak data rates of up to14 Mbit/s in the downlink. HSDPA willsoon be complemented by high speed uplinkpacket access (HSUPA), which will providepeak data rates of over 5 Mbit/s in the uplink.
Capacity vs costWhile HSxPA technologies will deliverhigher throughput and capacity in the radioaccess network, high capacity in itself is notsufficient. Extra capacity must be delivered ina cost-effective way, minimizing the cost-per-bit or the annualized cost-per-subscriber tomaximize profits. Mobile operators mustcontinuously evaluate the business case forindividual or groups of services in terms ofpotential revenue and the additional networkinvestment required. On the revenue sidethere will always be an upper limit on howmuch consumers and businesses can pay forservices. Therefore operators must minimizethe costs associated with delivering new ser-vices – particularly the cost-per-bit.
Although not immediately obvious, thespecific technologies used in mobile hand-sets can be a major factor in determining the cost-per-bit or annualized cost-per-
subscriber. The HSDPA standard includesseveral different categories of implementa-tion, which define specific configurationsand performance levels. A technology andeconomic analysis carried out by InterDigitalreveals that the lowest cost-per-bit can beachieved by deploying category 10.
Category 10 is the fastest mode of HSDPA.It can achieve downlink speeds of up to14 Mbit/s, but it also requires the deploymentof an advanced receiver design in mobiledevices. By contrast, the first generation ofHSDPA data cards and handsets will onlysupport up to category 6 due to the inherentperformance limitations of the rake-basedreceivers that are being used. This corre-sponds to a maximum data rate of 3.6 Mbit/s.
HSDPA uses multiple codes with lowspreading factor. This leads to multi-codeand inter-symbol interference that limits thedata rate that can be achieved with a rakereceiver. An advanced receiver addresses thisinterference by using a chip-level equalizerthat restores the orthogonality of the receivedcodes and can ultimately support category 10data rates of 14 Mbit/s.
An advanced receiver that uses a channelestimation-normalized least mean square(CE-NLMS) equalizer delivers superior per-formance in terms of throughput and capac-ity when compared with a rake receiver.Channel estimation enhances the perfor-mance of the NLMS equalizer in high-mobility environments. This advancedreceiver is scalable and can support up to and
Advanced receiver maximizesHSDPA profitability
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Fig. 1(a). CE-NLMS equalization boosts data throughput when the ratio of cell power to background noise (Ior/Ioc) is greater, as occurs in the centre of a cell. No receiver diversity isused in this example. (b). Receiver diversity further boosts the performance of CE-NLMS equalization.
Deploying category 10 HSDPAterminals with advanced receivers canhelp operators to minimize the cost-
per-bit of data services. BehroozLessani of InterDigital explains.
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including category 10.Figure 1(a) shows howhigher throughput canbe achieved with anadvanced receiver ver-sus a traditional rakereceiver for HSDPAcategories 6, 8 and 10.The data are for aVA120 channel modelcorresponding to theuser moving at a speedof 120 km/h.
Receive antennadiversity will also play amajor role in mitigating the effects of inter-cell interference – thereby improving perfor-mance at cell edges. An advanced receiverthat combines an equalizer with receivediversity will therefore deliver the highestperformance as shown in figure 1(b).
The HSDPA advanced receiver is availableas a co-processor chip that can be deployedwith existing UMTS R99/R4 hardware. It canalso be supplied as intellectual-property blocks,which can be licensed and integrated within asingle R5 chip. The co-processor has beendesigned specifically to minimize the amountof customization at the interface between theHSDPA co-processor and the R4 chip.
Economic network modelAn economic model of a completeW-CDMA/HSDPA network illustrates howan advanced receiver can reduce the cost-per-bit. This model covers the major urban areasof central London, encompassing 369 km2
with a user density of 1000 users/km2. Themodel describes the entire mobile networkincluding base station sites, backhaul and thecore network – both circuit-switched voiceand packet-switched core networks. All otherrelevant capital and operating expenditureshave also been accounted for in the model.
Particular attention was paid to modellingand costing the backhaul from base-stationsites to the first node in the network. This isvital because operators must ensure that thereis sufficient backhaul capacity to match the
instantaneous throughput demanded by thehighest HSDPA categories.
The London scenario is modelled over a 10-year operation period for one of five mobileoperators in the UK market. The modelassumes the highest penetration of HSDPA-enabled terminals in any given year in order todemonstrate the potential impact of anadvanced receiver design on the cost-per-bit.
The data and voice traffic loads used in themodel were derived from projections fromindustry sources such as the UMTS Forum,Ovum, Strategy Analytics and Frost &Sullivan. Towards the end of a 10-year cycle,high-capacity scenarios are assumed whereradio cells are filled with data only – or acombination of voice and data. Otherassumptions include a data traffic mix ofemail, web browsing, FTP and streamingwith 80% of the traffic in the downlink.Macrocells are first used to meet the trafficrequirements. However, when additionalcapacity is required, the model introduces anunderlay of over-the-rooftop microcells. Themodel computes the total cost of the networkand then compares cost-per-bit for a scenariowhen the network is loaded with mobiledevices equipped with an advanced receiveras against more traditional rake receiver-based terminals.
The economic benefits of an advancedreceiver for both data-only and mixed voiceand data scenarios are shown in figure 2. For adata-only scenario (including VoIP), a saving
of up to 70% in cost-per-bit over UMTSRelease 99/Release 4can be achieved whenusing advanced receiverdesign in mobile termi-nals for higher HSDPAcategories. Conversely,no economic improve-ments can be gainedwith rake-based termi-nals for categorieshigher than 6. Asbefore, the best perfor-mance in throughput
or the lowest cost-per-bit is achieved througha combination of NLMS equalizer and imple-mentation of receiver diversity.
Figure 3 reveals that the lowest annualizedcost-per-subscriber can be achieved with acombination of advanced receiver and cat-egory 10 HSDPA. The results also indicatethat category 8 delivers most of the perfor-mance and could be a possible sweet spot formobile operators before upgrading to cat-egory 10 for maximum performance. Anadvanced receiver provides this kind of scal-ability feature in mobile devices right fromthe beginning.
The higher throughput and capacityenabled by an advanced receiver also offersmobile operators more flexibility in deploy-ment and allows them to trade off capacityfor site separation or vice versa whenrequired. For example, a new operator offer-ing broadband wireless data services will beable to use larger site separations to achievea given capacity. Alternatively, an incumbentmobile operator can get more out of its exist-ing sites and reduce the need to deploy addi-tional microcell sites.
These economic and performance benefitsare just a few examples of the overall advan-tages of an advanced receiver. Other key userbenefits include a more seamless experienceacross 3G and WLAN because of the higherdata throughput and increased device batterylife due to much higher power efficiency.www.interdig i ta l .com
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Fig. 3. The annual cost-savings of implementing HSDPA versus R99/R4 increase with time.
Fig. 2. The cost-per-bit savings of HSDPA versus R99/R4 can be increased by using two receive antennas. Savings can be achieved on both voice and data transmission.
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By Robin Burton of SensustechWhile mobile markets in most developedcountries have reached saturation levels, roam-ing users provide a continually refreshedsource of new revenue for operators. Roamersare often higher-value customers than domes-tic subscribers thanks to higher roaming ratesand because roamers tend to make more use ofmobile-phone services. For some operators,especially in small nations or internationallyimportant holiday destinations, roamers canrepresent a significant portion of their revenue.
Not surprisingly, the competition forroaming is heating up. In the past, an opera-tor would charge all foreign operators thesame roaming rate. However, this is changingand many operators now negotiate roamingagreements based on various criteria.
Price is clearly an important factor becauseindividual operators want to secure as large aslice of roaming revenues as possible. Qualityof service is also an important factor becausepoor service can lead to lost roaming revenues.In a recent visit to Hong Kong, for example, Iwas connected to my operator’s preferred net-work when I switched on my phone. However,the voice quality was so poor that I manuallyselected an alternative network. I had to repeatthis for the duration of my stay, resulting inirritation for me and a loss of revenue for my
network’s chosen partner. If an operator canoffer high-quality service levels in places whereroamers are likely to be – and can documentthis network performance – it should be ableto attract roaming partners by guaranteeingbetter quality and higher rates of usage.
Winning statisticsThe roaming market is dynamic, with newcustomers arriving constantly by road, rail, seaand air. Each and every roamer must beacquired, retained and persuaded to use asmany services as possible. Operators can seehow many subscribers they are winning bylooking at statistics generated from theirswitches. They can also see, in broad terms,what sort of overall levels of quality the sub-scriber is experiencing in terms of droppedcalls and other measures of network quality.However, this will not tell an operator howwell their competitors are doing – and it willnot provide any insights into why competitorsare winning business or what the operator cando to increase its share of the roaming market.
To get a meaningful picture of the roamingmarket, operators must measure the roam-ing experience as directly as possible. Theymust determine which networks are acquir-ing roamers at key points including points-of-entry such as airports; hotels; conference
venues; key business districts; and exits fromunderground railways and other areas whereroamers are likely to re-register to a network.
The best way of gathering all this informa-tion is to use a device such as Sensustech’sPerformance Analysis Mobile (PAM), whichemulates roamer behaviour while gatheringthe relevant information. The PAM behaveslike a subscriber by continually attempting tomake and receive voice and data calls – allunder the central control of a remote server.
PAMs can be fitted with roaming SIMcards that allow the device to connect to allpotential roaming networks. They can thenbe fitted to vehicles such as buses or taxis thatoperate in areas and routes where roamers aretypically found. Or they can be fitted to ded-icated vehicles that drive defined routes.
As these units move around they can con-tinually re-register themselves to see whichnetwork acquires them. This information,together with location, builds up a pictureof the amount of roaming traffic that eachcompeting operator is likely to acquire fromincoming roamers. It can also reveal areaswhere networks are losing potential roamers.
Once they have been acquired by the net-work, the quality of service enjoyed byroamers can also be determined. Typical mea-surements of absolute quality from a sub-scriber’s perspective include network coverage,dropped call rates, call clarity mean opinionscore (MOS), data throughput speeds andlatency. The relative quality of a network canthen be inferred by making direct compar-isons against competing local networks.
The absolute quality of experience willdetermine the amount of time that a roamerspends talking and the degree to which heuses data services. Relative quality will deter-mine his overall satisfaction with the serviceand the degree to which more experiencedroamers are likely to manually switch net-work. Good relative quality could ultimatelyallow a network to capture roamers who aredissatisfied with competing networks.
PAMs can also measure customer experi-ence criteria such as overall coverage, droppedcalls and call clarity. Data gathered from allnetworks can be compared to yield bothabsolute and relative measures of quality.
A map of quality parameters can be prod-uced with a focus on regions used by inter-national business travellers and tourists. Vitalareas can then be subjected to special attention– gaps can be plugged and key infrastructurecan be made as resilient as possible. A PAMunit can also be placed in a roaming partner’snetwork to ensure that agreed levels of serviceare delivered and to troubleshoot and resolveany outstanding issues between partners.www.sensustech.com
NETWORK OPT IMIZAT ION
Roamers refreshtired mobile markets
The Performance Analysis Mobile can be installed in a taxi or other vehicle to monitor the performance of competing networks.
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Concerto v6 benefitsfrom Culham mergerBy Hamish JohnstonVector Fields has released version 6 of itsConcerto software for the design and simula-tion of RF, microwave and optical componentsand systems. The release comes a year afterVector Fields was acquired by Cobham Plc andthen merged with the electromagnetics armof Cobham-owned Culham Electromagneticsand Lightning. Wireless Europe spoke to VectorFields’ Chris Riley and Kevin Ward about thelatest version of Concerto and how the mergerhas brought fresh investment and new skillsto Vector Fields.
According to Ward and Riley, this latestversion of Concerto offers several majorimprovements over version 5. These includethe integration of Vector Fields’ Sopranoeigenvalue simulation, which is based on thefinite element method. “The finite elementsolver is extremely good for modelling highQ devices,” explains Ward. Soprano had beenpreviously available to Vector Fields cus-
tomers within its Opera-3D software for low-frequency design. Concerto already offersboth finite-difference time-domain (FDTD)and method-of-moments solvers and accord-ing to Riley it is the only product on the mar-ket that offers all three capabilities.
Version 6 also features an improvedOptimiserPlus feature for Concerto’sQuickwave FDTD solver. OptimiserPlus linksdirectly to Concerto’s 3D Geometric Modeller,which defines the geometry and associatedproperties of the model. Riley claims theimproved optimization can reduce simulationtimes by a factor of two to five times.
Kevin Ward told Wireless Europe that areduction in computation time is an impor-tant feature because users want to solveincreasingly complex problems. To this end,Concerto v6 is available in a 64-bit Linuxversion, which removes any software limita-
tions on the amount of memory available toConcerto. “This allows the modelling oflarger and larger problems,” says Ward.
Ward says that Concerto is already verycompetitive with other software in terms ofits ability to solve large benchmark problems– particularly large antenna models. “It ismore memory efficient and often it solvesproblems faster,” says Ward.
Concerto’s method-of-moments solver iscalled Clasp and it is updated in v6 with newpre- and post-processing tools. Clasp wasoriginally developed at Culham and was inte-grated into previous versions of Concerto.According to Ward, this initial contactbetween the two companies eventually ledto the acquisition and merger.
“The Culham people that have joined VFhave expertise in high-frequency computa-tional electromagnetics – whereas the exper-tise at VF tends to be at lower frequencies,”explains Ward. “So it was a very nice matchto bring the two together. The Culham peo-ple also brought a lot of expertise in solvinglarge electromagnetic problems and that isone area that we are looking at for thefuture,” explains Ward. www.vectorf ie lds.co.uk
SOFTWARE
Reduction in computation timeis important because userswant to solve increasinglycomplex problems
Team Up With EuMW2006It’s a new venue, a new location, and an extended format as the home city of Manchester United Football Club plays host to the 9th European Microwave Week.Now extended to SIX days the Week has ONE goal — to offer FOUR strong, responsive and challenging conferences, complemented by ONE established exhibitionfeaturing international players, and a vibrant social agenda. Europe’s premier RF and Microwave event kicks off at the G-Mex/MICC Complex on 10 Septemberthrough to 15 September and will showcase the latest trends and developments that are widening the field of application of microwaves.
THE EXHIBITIONThe European Microwave Exhibition is central to the week
• International Companies — catch up with the premier industry names from around the globe• Leading-edge Technology — exhibitors will showcase the latest product innovations, offering demonstrations and the chance to talk technical with experts• Technical Workshops — get first hand technical advice and guidance from the experts
THE CONFERENCESChoose from four separate but complementary conferences
• European Microwave Conference (EuMC) – 10-15 September• European Conference on Wireless Technology (ECWT) – 10-12 September• European Microwave Integrated Circuits Conference (EuMIC) – 10-13 September• European Radar Conference (EuRAD) – 13-15 September
Plus Workshops and Short Courses
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European Radar Conference The 36th European Microwave Conference Formerly GAAS SymposiumThe European Conference onWireless Technology
2 5P R O D U C T S
DC blocks boost tower ampsA family of DC blocks for wirelessapplications in the 0.4–3.0 GHz frequencyrange are new from MECA. The RoHS-compliant components are available in 7/16DIN, N, BNC & TNC configurations withRF power ratings to 500 W and 2.5 kW peakpower. The blocks have breakdown voltageratings of up to 2.5 kV and MECA says thatthey are ideal for eliminating unwanted DCvoltages or surges to tower-top amplifiers.www.e-meca.com
Base station operates ontwo standardsSiemens Communications has launched theMulti-Standard Base Station (MBS) systemthat enables mobile operators to integrateGSM and W-CDMA radio networkelements on a single modular platform.
According to Siemens the MBS can beused to upgrade installed GSM base stationsto support W-CDMA for minimal cost andeffort. The upgrade is achieved by adding asmall slide-in radio server unit (RSU) to anexisting rack. The RSU is used incombination with Siemens’ remote radiohead (RRH), which can be mounted easilyon a roof or tower.www.siemens.com
Jumper cables resist fireRadio Frequency Systems (RFS) hasunveiled a new line of jumper cables thatcan be used to make RF connectionsbetween main feeders, antennas and systemequipment. Polyvinyl chloride (PVC)components have been eliminated from thecables and a new cable-to-connector union
is used. According to RFS, this gives thecables superior performance in fires.
Conventional jumper cables employmoulded PVC caps to provide mechanicalsupport between the cable and connector.These have been replaced by an advancednew connector design that allows the directcoupling of the cable and end-connector.
RFS says the new jumper cables have beenoptimized to provide improved electricalperformance, while ensuring that the entirejumper assembly is flame-retardant. Inaddition, the new cable/connector interfaceis said to deliver better return-loss results andimproved intermodulation performancewww.rfswor ld.com
DSP is for 3G and beyondA new multicore digital signal processor(DSP) from Freescale Semiconductor is saidto deliver high levels of performance thatcan be used to reduce system costs andboost channel densities in next-generationwireless infrastructure equipment.
The new DSP can be used in variouswireless applications including voicetranscoding and baseband cards for layer-twoprocessing in radio network controllers(RNCs). The device combines four StarCoreDSP cores, which each operate at 1 GHz. TheDSP includes 10.5 Mbyte of memory, whichFreescale claims is the largest embeddedmemory available in a single DSP package.www.freescale.com
PA is for linear EDGE handsetsRF Micro Devices (RFMD) has unveiled theRF3159 quad-band power amplifier (PA)module for use in EDGE handsets thatemploy linear transmit architectures.Described as a high linearity quad-band
GSM/GPRS/EDGE PA, the module is fullymatched for ease of implementation and issupplied in a 6 × 6 mm package. According toRFMD, the gain and linearity features of theRF3159 will enable handset manufacturers tooptimize their designs in terms of linearity,efficiency and output power. The module isaimed at the final amplification stage in adual-mode GSM/GPRS/EDGE mobiletransmit line-up that operates in the824–915 MHz and 1710–1910 MHz bands. www.rfmd.com
Transceiver chip is forHSDPA handsetsSony has extended its range of transceiverchips for 3G handsets with the introductionof a single-chip multi-standard transceiverthat operates in five frequency bands.Covering the 850, 900, 1700, 1900 and2000 MHz bands, the CXA3361AGG isdelivered in a 6 × 6 mm square package andis compliant to HSDPA category 6.
The device is based on Sony’s SiGeBiCMOS technology and integratesupconverter and downconverter mixers, RFgain control amplifiers and a baseband PGAand LPF. Internal matching to the externalSAW filters in both transmit (Tx) and receive(Rx) chains is achieved, which minimizes thenumber of external components required.
A synthesizer circuit comprising a VCO,inductors and varactors is also integratedonto the chip. The Tx section features adirect modulation transmitter, integratedvariable-gain amplifiers (VGA) and has aminimum dynamic range of 80 dB. The Rxsection combines a direct conversionreceiver, integrated channel filter andintegrated DC offset compensation.www.sony.net
Surface-mount capacitorshave very small footprint A new family of leadframeless tantalumcapacitors for use in mobile phones hasbeen released by Vishay Intertechnology.Offering face-down terminations, the 298DMicroTan surface-mount capacitors areavailable in capacitance values from 1 µF at16 V to 47 µF at 4 V. Supplied in 0603 and0805 packages, the capacitors are said tooccupy less space than competitors. Thecomponents are intended for use in signalprocessing and power managementapplications in mobile phones and otherportable electronics. www.v ishay.com
w i r e l e s s e u r o p e wire less. iop.org J u n e / J u l y 2 0 0 6
HANDSET &INFRASTRUCTURE
2 6 T H E F U T U R E
How is HSDPA progressing at Agere?In February we announced the sampling of ourHSDPA chipset and we are now in the middleof the handset-development process with ourlead customers. We have demonstrated layer-one HSDPA performance of 3.6 Mbits/s in par-allel with standard 384 kbit/s on the uplink anddownlink and voice calls – all on the chipset.Integration efforts are going on right now tobuild complete handsets with more than onehandset manufacturer.
Why begin with 3.6 Mbit/s HSDPA ratherthan 1.8 Mbit/s?We believe that 1.8 Mbit/s is just not goodenough and the market needs precisely3.6 Mbit/s. The reality is that 1.8 Mbit/s sharedover a number of users does not really providemuch of an advantage over the Release 99 datarate of 384 kbit/s. While HSDPA can achievedata rates higher than 3.6 Mbit/s, networks arenot ready and will not be ready for a while. IfHSDPA were deployed with 7.2 Mbit/s in thedownlink and 384 kbit/s in the uplink, networks would struggleto deal with the highly asymmetrical nature of the uplink anddownlink data rates.
Today, most backbone networks cannot support large num-bers of high-speed data users. These networks were designed toprovide voice channels and then were upgraded to accommo-date data traffic. Deploying HSDPA at 3.6 Mbit/s allows oper-ators to employ their current network. Once the network isupgraded, the backbone is improved and the servers are in placeto deliver high-speed data services, 3.6 Mbit/s equipment willallow subscribers to take full advantage of these improvements.The next step is to roll-out HSUPA in conjunction withHSDPA at 7.2 kbit/s.
Are advanced receivers crucial to delivering HSDPA?Advanced receiver technology can improve receive sensitivityby about 3 dB, which boosts the range of HSDPA transmissionby 25%. Improved sensitivity gives the handset maker variousoptions: they could deploy multiple receivers, create a moreintelligent receiver, or implement receiver diversity methods.
There is much debate about whether a normal receiver can
be used to achieve 3.6 Mbit/s – some say it’spossible and others say it isn’t. We have demon-strated 3.6 Mbit/s with our advanced receiver.It offers greater range and will make handsetsmore robust in real-life use, where signal con-ditions are rarely ideal. We believe that ourtechnology can widely eliminate the droppedcalls associated with normal receivers. Thiswould boost network performance without theneed for operators to install more base stations.I’m confident that a boost in receive sensitivityof 3 dB can be used to compensate if the cellplanning is not very good.
Is the chipset aimed at handsets or datacards?It’s aimed at both. Datacards are a naturalapplication for higher data rates, whereas oper-ators are eager to deploy HSDPA handsetsbecause they can be used to improve spectrumutilization and reduce round-trip delay.Reduced delay can improve the quality ofspeech in conversations. Currently there isabout 100–120 ms delay in W-CDMA but
HSDPA will reduce this to about 50–60 ms range.
What applications will flourish thanks to HSDPA?Music downloads are one application that could benefit fromHSDPA. But operators must also ensure that digital music canbe played on handsets and that digital rights management isimplemented. HSDPA will also improve the general browsingcapabilities of mobile phones. WAP is a cumbersome technol-ogy and I would like a real HTML browser on my phone –which is possible with HSDPA. I believe that the effect ofHSDPA on mobile Internet usage will be similar to the changesin web usage that occurred when broadband connectionsreplaced dial-up modems. Before broadband, web pages didnot include many pictures, animations or video clips. Similarly,Internet browsing and streaming are becoming importantmobile applications. While many of these applications are pos-sible today at lower data rates, the packet-based nature ofHSDPA allows operators to deliver these services in a more effi-cient and cheaper way. ■
Interview by Hamish Johnston, editor of Wireless Europe.
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HSDPA benefits fromadvanced receiver
Roman Polz of Agere Systems explains why 1.8 Mbit/s is just not good enough for HSDPA.
Roman Polz: “The effect of HSDPA onmobile Internet usage will be similar tothe changes in web usage thatoccurred when broadband connectionsreplaced dial-up modems.”
EXPANDINGYOUR CELLULARNETWORK?
Read all the latestexpert opinion andadvice in the BaseStation Evolution: IOP Report.
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Written by engineers and executives from leading companies in theradio-infrastructure supply chain, these articles cover the followingkey topics:
• network testing and optimization • future technologies • HSDPA • backhaul strategies • base station installation • core network
This valuable 12 month perspective on base station evolutioncosts just £50.00/$90.00/¤72.50 for electronic delivery or£99.00/$178.20/¤143.55 for the printed version.
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TV and mobile radio are uniting. Mobile TV standards such as DVB-H, T-DMB or MediaFLO™ bring movies to the mobile phone screen, and Rohde & Schwarz is ready to support the convergence. We‘ve been at the forefront of both technologies for years. As a market leader in mobile radio test & measurement, as well as in broadcasting equipment, we offer you the best of both worlds. Phone developers and network operators alike can count on us for everything they need to bring this new technology to market
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2183_MobileTV_e_213x282.indd 1 29.05.2006 13:27:48 Uhr
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